1. Field of the Invention
This invention relates generally to safety measures directed to protecting workmen performing service and maintenance in connection with high voltage power transmission and distribution lines and particularly to an apparatus and method for testing the insulating quality of elongated, insulated rods connected to tools used during such service and maintenance procedures.
2. Description of the Related Art
For many decades power company workmen have performed various service and maintenance procedures in connection with energized power transmission and distribution lines referred to as live-line work in the industry. OSHA has published various rules concerning such work to attempt to insure the safety of such workers.
In addition to certain protective clothing often worn by the worker, certain specific procedures require tooling made with conductive material to be employed in contact with or close proximity to the live power line or associated parts thereof. For example, this includes clamps, cutters, cotter pin pullers and the like. Such tooling is connected to the end of an insulated elongate handle which is held at the opposing end by the worker for manipulation of the tool. Such handles are made of an insulating material and typically consist of long, generally cylindrical rods. The minimum length of the insulated handle is directed by OSHA standards and is related a voltage value determined by the voltage of the power line upon which the work is be done. Such rod-like, insulated handles may range from a few feet for 15 kv applications and up to 20 feet for very high voltage applications such as 500 to 765 kv lines. These insulated handles are referred to as “hot sticks” in the industry. Therefore the term “hot stick” as used herein is meant to refer to such insulated handles as described above.
As is well-known in this field, work in high voltage power transmission and distribution lines is very dangerous and requires appropriate safety measures and caution. Any failure in properly exercised safety may cause mistakes or accidents which often cause severe injury or death.
It is also well-known that without the appropriate protective measures, a high voltage gradient can cause electrical arcing which may travel significant distances if a conductive path between the voltage source and a lower voltage, such as ground, is established. Voltage gradient, sometimes referred to as electrical field intensity, is measured in voltage per unit of length. The very nature of live line work performed by those using hot stick tooling therefore requires appropriate testing procedures for the hot sticks prior to initial use as well as periodically after use to assure the rated safety value is valid to avoid the serious consequences of “flashover” or arcing traveling down the hot stick to the user holding the opposing end.
Currently the testing devices and method used for hot stick compliance testing have been found to be less than satisfactorily effective to detect certain defects which have the potential to cause a flashover or electric arc to be generated during use and result in serious injuries or death. While the number of such “flashover” incidents is relatively low, the catastrophic outcome requires a practical solution be found which to date has eluded those skilled in the art.